1. Field of the Invention
The present invention relates to a rotary bottle blowing machine, and more particularly to a blow molding device for the rotary bottle blowing machine.
2. Description of the Prior Art
FIGS. 1 and 2 show a device for blow molding containers, which is disclosed in U.S. Pat. No. 8,100,688, wherein the blow molding station 10 essentially comprises a drive shaft 12 rotatably disposed on a support structure 11. On the support structure 11 are further fixed a stationary mold portion 13 and a movable mold portion 14 capable of pivoting with respect to the stationary mold portion 13. At the bottom of the stationary mold portion 13 is formed a cam track 131. The drive shaft 12 is connected to the movable mold portion 14 by a first connecting member 15 which is perpendicular to the drive shaft 12, and is connected to a base mold portion 17 via a second connecting member 16 which is located in a direction different to the extending direction of the drive shaft 12. At the base mold portion 17 is provided a cam 171 which is movably disposed in the cam track 131. When the drive shaft 12 rotates, the first and second connecting members 15, 16 will push the movable mold portion 14 to pivot with respect to the stationary mold portion 13, meanwhile, pushing the base mold portion 17 to move up and down by moving the cam 171 along the cam track 131. The drive shaft 12 of the blow molding station 10 generally uses the connecting members 15, 16 which extend in different directions, to open or close the movable mold portion 14, and to move the base mold portion 17 up and down, respectively. Therefore, the connecting members 15, 16 of the drive shaft 12 become the weak point of the whole blow molding station. Furthermore, both ends of the connecting members 15, 16 are pivotally connected to the drive shaft 12, the movable mold portion 14 and the base mold portion 17. The pivotal connecting points will affect the smoothness, accurateness and efficiency of the operation of the blow molding station. The requirements on the structural accuracy and quality are very strict and difficult to control, therefore, the device for blow molding containers as disclosed in U.S. Pat. No. 8,100,688 is difficult to assemble, high cost, and the structural accuracy is difficult to control.
FIGS. 3 and 4 show another device for blow molding containers, which is disclosed in U.S Application No. 20120177771A1, wherein the blow molding station 20 is provided with a fixed platform 21, a stationary mold portion 22 fixed at one side of the fixed platform 21, and columns 211 disposed at another side of the fixed platform 21 and connected a base mold portion 23. The fixed platform 21 is further provided with a first drive shaft 24 and a second drive shaft 25. The first drive shaft 24 is connected to a movable mold portion 26 via a first crank 241. The movable mold portion 26 includes a vertical abutment 261, the first crank 241 is connected to a second crank 251 fixed to the second drive shaft 25 by a connecting member 27 which is arranged perpendicular to the extending direction of the first and second drive shafts 24, 25, and both ends of the connecting member 27 are connected in a pivotal manner. The second drive shaft 25 is provided with a strut 252 formed in the shape of the abutment 261. To move the movable mold portion 26 and the base mold portion 23, it has to use a drive source to move the base mold portion 23 up and down, and another drive source to rotate the first drive shaft 24, therefore, the structure of the device of U.S Application No. 20120177771A1 is too complicated and high cost. During operation, the first drive shaft 24 rotates the first crank 241 and the movable mold portion 26, so as to control opening and closing of the mold. Meanwhile, the connecting member 27 connected to the first crank 241 moves the second crank 251, the second crank 251 then rotates the second drive shaft 25 and the strut 252. When the movable mold portion 26 performs mold-closing motion, the strut 252 also moves and will stop against the abutment 261 of the movable mold portion 26, so that the movable mold portion 26 can stably take up the blow-molding force during blow molding process, ensuring molding accuracy.
However, in addition to the disadvantages of complicated structure, high cost, and requiring two drive sources to open and close the mold and lift the base mold portion, the device of U.S Application No. 20120177771A1 also has to use the connecting member 27 which is perpendicular to the extending direction of the first and second drive shafts 24, 25 to move the strut 252. The connecting member 27 becomes the weak point of the whole structure, and both ends of the connecting member 27 are also connected in a pivot manner, as a result, the requirements on the structural accuracy and quality of device of U.S Application No. 20120177771A1 are very strict and difficult to control.
FIGS. 5 and 6 show another device for blow molding containers, which is disclosed in German Patent application No. DE102008045569A1, wherein the blow molding device 30 employs a drive source 31 to rotate a control member 32 which includes a first cam 321 and a second cam 322. The control member 32 is connected to a clamping drive member 34 by a connecting member 33. The clamping drive member 34 is provided at one side thereof with a first pivot 341 and a second pivot 342 which are abutted against the first and second cams 321, 322, respectively. Another side of the clamping drive member 34 is pivoted to a first and a second driven rods 343, 344 which are connected to two mold portions 35, 36, respectively. The drive source 31 rotates the control member 32, when the control member 32 rotates, the first and second cams 321, 322 rotate synchronously, to change the positions of the first and second pivots 341, 342 with respect to the first and second cams 321, 322, consequently making the clamping drive member 34. Then, the movement of the clamping drive member 34 can further change the positions of the first and second pivots 341, 342, thus making the first and second pivots 341, 342 move the two mold portions 35, 36 to carry out mold opening and closing.
However, the device disclosed in German Patent application No. DE102008045569A1 still can't use a single drive source to perform mold lifting and mold closing. In addition to the fact that the control member of the blow molding device 30 has to use the drive source to move the clamping drive member, the clamping drive member also has to be provided with the first and second pivots 341, 342 in order to perform mold closing. Since the mold portions 35, 36 are driven by the clamping drive member 34 in an indirect manner to perform mold closing and opening operation, which will reduce the work efficiency and operation accuracy.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.